"java.lang.ClassCastException: org.hibernate.ejb.HibernatePersistence" when packaging Hibernate into EAR

Issue

I have an ear containing library that fall in conflict with the same libraries inside Jboss (hibernate-entitymanager-3.4.0.GA, hibernate-search-3.1.1.GA, hibernate-validator-3.1.0.GA)
I think what  is going on is that the same classes are being loaded by different class loaders leading to ClassCastExceptions.

java.lang.ClassCastException: org.hibernate.ejb.HibernatePersistence
      at org.jboss.ejb3.entity.PersistenceUnitDeployment.start(PersistenceUnitDeployment.java:245)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:585)
      at org.jboss.ejb3.ServiceDelegateWrapper.startService(ServiceDelegateWrapper.java:103)
      at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289)
      at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245)
      at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:585)
      at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
      at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
      at org.jboss.mx.server.Invocation.invoke(Invocation.java:86)
      at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
      at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
      at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978)
      at $Proxy0.start(Unknown Source)
      at org.jboss.system.ServiceController.start(ServiceController.java:417)      ...
java.lang.ClassCastException: org.jboss.ejb3.stateless.StatelessContainer
      at org.jboss.ejb3.security.AuthenticationInterceptorFactory.createPerClass(AuthenticationInterceptorFactory.java:44)
      at org.jboss.aop.advice.AspectFactoryDelegator.createPerClass(AspectFactoryDelegator.java:107)
      at org.jboss.aop.Advisor.addPerClassAspect(Advisor.java:569)
      at org.jboss.aop.advice.ScopedInterceptorFactory.create(ScopedInterceptorFactory.java:72)
      at org.jboss.aop.Advisor.createInterceptorChain(Advisor.java:618)
      at org.jboss.aop.Advisor.pointcutResolved(Advisor.java:888)
      at org.jboss.aop.Advisor.resolveMethodPointcut(Advisor.java:650)
      at org.jboss.aop.ClassContainer.createInterceptorChains(ClassContainer.java:248)
      at org.jboss.aop.ClassContainer.rebuildInterceptors(ClassContainer.java:115)
      at org.jboss.aop.ClassContainer.initializeClassContainer(ClassContainer.java:58)
      at org.jboss.ejb3.EJBContainer.processMetadata(EJBContainer.java:342)
      at org.jboss.ejb3.SessionContainer.processMetadata(SessionContainer.java:140)
      at org.jboss.ejb3.Ejb3Deployment.processEJBContainerMetadata(Ejb3Deployment.java:293)
      at org.jboss.ejb3.Ejb3Deployment.start(Ejb3Deployment.java:357)
      at org.jboss.ejb3.Ejb3Module.startService(Ejb3Module.java:83)
      at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:289)
      at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:245)
      at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:585)
      at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
      at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
      at org.jboss.mx.server.Invocation.invoke(Invocation.java:86)
      at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
      at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
      at org.jboss.system.ServiceController$ServiceProxy.invoke(ServiceController.java:978)
      at $Proxy0.start(Unknown Source)
      at org.jboss.system.ServiceController.start(ServiceController.java:417)      ...